Merge branch 'wip/chergert/gdk-macos-gl-renderer' into 'master'

macos: add more aggressive clip to transparent subview

See merge request GNOME/gtk!2762

gdk/macos/GdkMacosCairoSubview.c

@@ -32,6 +32,12 @@
 
 @implementation GdkMacosCairoSubview
 
+-(void)dealloc
+{
+  g_clear_pointer (&self->clip, cairo_region_destroy);
+  [super dealloc];
+}
+
 -(BOOL)isOpaque
 {
   return _isOpaque;
@@ -95,6 +101,21 @@
   cr = cairo_create (dest);
   cairo_translate (cr, -abs_bounds.origin.x, -abs_bounds.origin.y);
 
+  /* Apply the clip if provided one */
+  if (self->clip != NULL)
+    {
+      cairo_rectangle_int_t area;
+
+      n_rects = cairo_region_num_rectangles (self->clip);
+      for (guint i = 0; i < n_rects; i++)
+        {
+          cairo_region_get_rectangle (self->clip, i, &area);
+          cairo_rectangle (cr, area.x, area.y, area.width, area.height);
+        }
+
+      cairo_clip (cr);
+    }
+
   /* Clip the cairo context based on the rectangles to be drawn
    * within the bounding box :rect.
    */
@@ -168,4 +189,14 @@
   self->_isOpaque = opaque;
 }
 
+-(void)setClip:(cairo_region_t*)region
+{
+  if (region != self->clip)
+    {
+      g_clear_pointer (&self->clip, cairo_region_destroy);
+      if (region != NULL)
+        self->clip = cairo_region_reference (region);
+    }
+}
+
 @end

gdk/macos/GdkMacosCairoSubview.h

@@ -26,10 +26,12 @@
 {
   BOOL             _isOpaque;
   cairo_surface_t *cairoSurface;
+  cairo_region_t  *clip;
 }
 
 -(void)setOpaque:(BOOL)opaque;
 -(void)setCairoSurface:(cairo_surface_t *)cairoSurface
             withDamage:(cairo_region_t *)region;
+-(void)setClip:(cairo_region_t*)region;
 
 @end

gdk/macos/GdkMacosCairoView.c

@@ -78,6 +78,7 @@
 
 -(void)setOpaqueRegion:(cairo_region_t *)region
 {
+  cairo_region_t *transparent_clip;
   NSRect abs_bounds;
   guint n_rects;
 
@@ -87,6 +88,17 @@
   abs_bounds = [self convertRect:[self bounds] toView:nil];
   n_rects = cairo_region_num_rectangles (region);
 
+  /* First, we create a clip region for the transparent region to use so that
+   * we dont end up exposing too much other than the corners on CSD.
+   */
+  transparent_clip = cairo_region_create_rectangle (&(cairo_rectangle_int_t) {
+    abs_bounds.origin.x, abs_bounds.origin.y,
+    abs_bounds.size.width, abs_bounds.size.height
+  });
+  cairo_region_subtract (transparent_clip, region);
+  [(GdkMacosCairoSubview *)self->transparent setClip:transparent_clip];
+  cairo_region_destroy (transparent_clip);
+
   /* The common case (at least for opaque windows and CSD) is that we will
    * have either one or two opaque rectangles. If we detect that the same
    * number of them are available as the previous, we can just resize the